Carbon Steel Clad 2

[bmoorthy]

This is a bit funny, but still.

If we have a high pressure high thickness vessel in HIC service, is it OK to take a 6mm CS (HIC Tested and extra low sulphur) and explosion bond it with an ordinary CS plate and Make CS to CS clad plate and roll it and form a vessel.

Would it not be economical as compared to having high thick CS Plate with Extra low sulphur and HIC tests etc.

Is this permitted norm or is this prohibited. Any guidelines?

 

[unclesyd]

There are some vessels made in a similar fashion, mainly by the Japanese and some work in Russia. There were discussions of using auto-fretting in the manufacture of these vessels. There was a paper some years back by one of the National Labs concerning the fabrication of Multilayer Vessels. Multi-layer Vessels were quite common in NH3 plants.

Here is a discussion at a NACE conference with a little info on Multilayer Vessels.
See 5.7 Hydrocrackers

http://www.nace.org/nace/content/technical/ctw2k3minutes/stg34/teg205Xminutes.htm

One of the Forum members should have been there.

 

[unclesyd]

Got to thinking instead of writing.
You will not gain any thing unless you have a layer that is impermeable to H2 between the 2 plates as H2 will go thru 6 mm plate in about two vibrations of the molecule.
Once thru it would penetrate the support plate in no time and do whatever damage its going to do.

I can’t think of any metal that might work without presenting other problems. Tri-metals are quite limited in temperature and usually the a high expansion metal is on the outside, not sandwiched.

HIC certified steel isn’t that much more expensive if you can plan somewhat in advance. The consequences of not using it if needed makes seem very cheap.

 

[GenB]

And dangerous!

 

[vak]

I am glad that this question was asked. In fact i also had the same train of thought. Hence a star for the person for asking the question and a star for the first answer from UNCLESYD for the link.

The second answer is not all that convincing. Once a Ultra pure steel is in contact with fluid (containing H2 or H2S), i do not see how the H2 would diffuse and create problem.

I am not a metallurgist, but is it not true that Ultra pure Steel like Luken fine line steel are resistant to H2 diffusion and there by HIC resistant.

May be i am wrong but i also have to clear up some basics hence this post.

I did some THINKING and reading of MR 0175 and SOHIC NACE but could not link it with answer to the question as to whether it is prohibited to use.

 

[bmoorthy]

Thanks for your support VAK. But i found the explanation given by UNCLESYD was logical. But one more thing, we do not do HIC TEST for the CS portion of CLaded plate on the assumption that it is not susseptable to HIC cracks and hence it prevents ingress of H2.

I not a Metallurigist either, In fact i was looking for some Metallurgy course online (good ones).

 

[unclesyd]

H2 will still diffuse but you have taken away or limited the components/conditions that are needed for certain failure mechanisms to start.
If the design conditions call for or even suggest the us of HIC resistant steel it would behoove one to use it.

Both H2 and He will diffuse through steel at known rates and are normally of no concern. H2 diffusion in steel is not a problem unless it plays a role, set by conditions or enviroment, in failure mechanisms. HIC, Blistering, H2 Assisted Fatigue are several.
HIC resistant steel will help prevent H2 from initiating a crack under known environmental conditions but has limited value in a situation where one could have a mechanical fatigue failure start and H2 move in to give assistance to the crack propagation rate. HIC resistant steel just extends the time to failure for this case where it is normally of little concern.
(He)diffuses and just keeps going.

 

[PVRV]

Apply an internal coating rather than cladding with CS; else clad with a material that is resistant to the anticipated corrosion type; that way I dont see where the H2 would come from.

Cheers

 

[JoeTank]

PVRV,
I have always assumed that H2 would easily diffuse through the coatings. Am I wrong about that?

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[bmoorthy]

If my understanding is correct, from the above post of unclesyd, then even in SS + CS clad plates H2 would diffuse. In which case the CS needs to be HIC tested steel.

Is this the case.

Is it required to test CS portion of SS + CS Clad steel for HIC test when the equipment is subjected to Sour service+ HIC service?

 

[unclesyd]

H will permeate anything if given time and driving force. You have a reversible and irreversible form of H permeation based on the substance being penetrated. There are coatings that slowdown the process, but H will win out. If you have H in a metal container under any conditions one should keep abreast of the current thinking and keep watch on the container. The effects of H damage can be almost instantaneous or long and drawn out.

Any design using H should be keep in the norm as results good or bad are time dependent and mostly unknown.

A case in point was that one time it was though that Cu would help prevent H damage, whoops not so. We had a failure in a Cu vessel exposed to H2.
A deoxidizer (316 SS) used H2 to reduce Cu shot in an old style inert gas system failed catastrophically while in service. At the time we couldn’t identify the failure mechanism in either case. When we got access to an electron microscope 20 yrs later both the samples pulled from our museum showed evidence of severe H damage.

We did things around H in 50's, 60's and 70's that you wouldn't even think about doing today.

Just be careful with H in a process situtation.

 

[PVRV]

No Corrosion, No H2 that why internal coating are applied, thats why SS is used (cladding) nothing to do with resistant to Hydrogen Damage.

Thats not to say that NACE-TM0284 or 177 for that matter should not be applied for CS, additionally that not to say that Sulphur / Calcium ratio is not important, else concentrations of Phosphourus and values Hardness values (200 BHN or 22 HRC).

Cheers

 

[bmoorthy]

PVRV, i think MR 0175 prohibits use of Coating/plating (used as for sole purpose of prevention of corrosion). As far as i recollect, coatings and linings are more prone for H attack and blisters out. A few years back i saw it in one of the electroplating (Technical) film.

 

[PVRV]

CS pressure vessels are internally coated else cladded with SS or other alloyed materials. It is not a question of H2 pentration rather,,,avoiding generation of H2 surely the CS should be NACE compliant and at times complimented with other sour service requirements.

The above is in responce to cladding CS over CS and the rather sad view that H2 diffuses through anything,,granted that is true to an extent but Id rather mitigate H2 generation while as increasing resistance to Hydrogen damage rather then figuring out a way to block atomic hydrogen.

Here is a suggestion to gain some prespective,,,lets start talking practical experience.

Cheers